This invention relates to a chair in which a seat and a backrest can make a rocking movement with synchronizing the seat and the backrest.
Conventionally, a chair of this kind has been so arranged that a seat and a backrest can make a rocking movement between an upright posture and a rearward tilted posture with synchronizing the seat and the backrest by a synchronized tilt mechanism equipped with a various kind of rocking devices. However, this kind of chair cannot change the rearward tilted posture. In view of the above problem, a chair has recently been developed in which a rocking range as an angle between an upright posture and a rearward tilted posture can be adjusted.
Some chairs of the above arrangement are provided with a mechanism to adjust the rocking range in a space from a center along back and forth to rearward of a supporting body or a seat frame locating under the seat and fixed to the upper end portion of the leg.
However, with the above arrangement if an operating member to adjust the rocking range is arranged at a front side of the seat that is accessible for a seated person, a transmitting mechanism to transmit an operating force of the operating member to an adjusting mechanism to adjust the rocking range that is arranged in a space from the center to rearward of the supporting body or the seat frame becomes complicated and large, thereby to be bulky as a whole.
Further, a highly-functioned chair that has been recently developed is provided with a mechanism to support a backrest, a mechanism to elevate a seat, a mechanism to mount a back cover on a backrest or other various mechanisms around a space from a center to rearward of a supporting body or a seat frame and a variety of components constituting the above mechanisms are arranged there. As a result of this, in order to arrange the adjusting mechanism near the above-mentioned mechanisms the adjusting mechanism has to be arranged at a position that does not interfere the other components, thereby to decrease a degree of freedom in design.